fix: update default Node.js version to 22

The withastro/action@v3 defaults to Node 20, which is insufficient for
upcoming Astro dependency updates (see PR hyperlight-dev#7). This sets Node 22
explicitly in the workflow and adds a .node-version file for local
development consistency.

Closes hyperlight-dev#9

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Signed-off-by: David Justice <david@justice.dev>

Author: devigned

.github/workflows/deploy.yml

@@ -24,6 +24,8 @@ jobs:
 
       - name: Build with Astro
         uses: withastro/action@v3
+        with:
+          node-version: 22
 
   deploy:
     name: Deploy

.node-version

@@ -0,0 +1 @@
+22